textproduct: Rapid City

KEY MESSAGES

- Chances for isolated showers and thunderstorms daily through the weekend; a few storms could be severe.

- Daily, low end rain chances last into next week.

- Warming up for the weekend with above normal temps lasting into next week.

UPDATE

Issued at 1013 PM MDT Fri Aug 28 2026

Westerly flow continues across the CWA as an upper ridge is parked across the Four Corners region. Several waves crossing the region are bringing unsettled weather to WY and the Dakotas. KUDX radar shows weak showers along the fringes of the CWA. Could see more isolated showers overnight, but overall it should remain a quiet night with temps dropping into the 60s. An upper wave now over southern ID/western WY will continue eastward toward the CWA tomorrow. Associate forcing could bring isolated showers and thunderstorms through the afternoon across NE WY/far western SD, but shear and instabilty are quite weak across most of the CWA. Both components are moderately better across NW/central SD. That, along with the timing of the wave, seems to favor these areas best for severe weather late Saturday afternoon into the evening. Hail and wind will both be primary threats.

DISCUSSION

(This Evening Through Friday) Issued at 110 PM MDT Fri Aug 28 2026

Latest satellite imagery shows moisture and clouds streaming into the area from the southwest, this gives hints as to what can be expected for the rest of today and this weekend. An upper level high pressure looks to slide to the east, this is giving the CWA southwest flow which opens the area up to the possibility for rain and storms.

So for the rest of today, moisture streaming over the mountains in Wyoming and the Black Hills will be a main source for any thunderstorm activity. Latest guidance has storms initiating later in the afternoon, say around 2 to 4PM. And once they develop, they will track eastward. Severe thunderstorms today can't be ruled out but the chances are low. The SPC has placed a marginal risk (level 1 of 5) of severe weather over the entire area today and the latest machine learning severe weather models give around 5 to 15% chance of storm cells being severe. The HRRR severe weather probability model puts an 8 to 16% chance of severe storms near the northern Black Hills and in the SD plains in the 4 to 9PM window.

For tonight and the weekend, hi res models keep trying to hint at another round of rain moving into NE WY during the overnight hours but confidence is low.

An upper level trough is expected to swing over Montana and North Dakota. This will bring continued chances for rain and storms to the CWA. So for Saturday afternoon, another round of showers and storms is likely to track northeast through NE WY and into western SD. And once again, those storms could be strong to severe with hail and wind being the main concerns. Sunday is looking like a similar set up with storms developing in WY and tracking into SD.

Afternoon temps will be warmer with highs in the upper 80s to mid 90s Saturday and Sunday. Overall, well above normal for late August.

For a quick glance at next week, lingering low end chances for daily passing showers and storms last well into next week but the overall pattern is still on the dry side. Above normal temps will continue as well with highs in the 80s to 90s.

AVIATION

(For the 06Z TAFS Through 06Z Saturday Night) Issued At 1009 PM MDT Fri Aug 28 2026

Showers will continue to move across portions of northeast Wyoming and western South Dakota during the overnight hours. An isolated thunderstorm or two will be possible with gusty/erratic winds. Transient MVFR conditions are possible around any heavier precipitation cores.

Another round of showers and storms will be possible tomorrow over northeast Wyoming and western South Dakota starting around 29/20z and lasting through the remainder of the forecast period. Both KGCC and KRAP may be impacted, so PROB30s have been added to the TAFs. Hail, frequent lightning, and gusty/erratic winds can be expected with any stronger convective cores. Transient MVFR/IFR conditions also expected around any heavier precipitation cores.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.